The influence of different forms and concentrations of potassium nutrition on growth and alkaloid metabolism in Catharanthus roseus seedlings

In order to investigate the effect of potassium (K) nutrition on secondary metabolism, Catharanthus roseus was treated by different concentrations and forms of K nutrition (KNO3 and K2SO4). The results showed that the concentration of applied K obviously affected plant growth and biomass accumulation, while K form had little influence. The concentration of alkaloids, including vinblastine in the leaves and catharanthine in the leaves or roots, had a significant increase, especially upon 80 and 100 mM K nutrition. The measurement of internal ion content using energy dispersive spectroscopy displayed that the increase of K element in leaves was tightly correlated with elevated alkaloid concentration. The transcript levels of G10h, Str, and Dat genes, encoding key enzymes in the alkaloid biosynthesis pathway, were significantly activated by applying P and tightly related to alkaloid accumulation. In conclusion, our results provided the physiological and molecular evidence that potassium could effectively regulate alkaloid metabolism in C. roseus.